NEURAL NETWORK MAXIMUM A POSTERIORI ANGLE DEMODULATION FOR SPREAD SPECTRUM COMMUNICATIONS AND FM RECEIVERS

NEW RESULTS INDICATE THAT A VLSI HOPFIELD NEURAL NETWORK CAN BE CONFIGURED TO QUICKLY SOLVE THE NONLINEAR INTEGRAL EQUATION DESCRIBING OPTIMUM, MAXIMUM A POSTERIORI (MAP) PHASE DEMODULATION. PERFORMANCE OF THIS DEVICE SHOULD BE SIGNIFICANTLY SUPERIOR TO THE WIDELY USED BUT SUBOPTIMUM PHASE LOCKED LOOP DEMODULATOR, WHICH ONLY PROCESSES HALF THE RELEVANT DATA SAMPLES. APPLICATION OF THE NEURAL NETWORK DEMODULATOR TO SPREAD SPECTRUM COMMUNICATION, WHICH IS INCREASINGLY USED IN MILITARY AND COMMERCIAL COMMUNICATION LINKS, AND TO STANDARD FREQUENCY DEMODULATION IS CONSIDERED. MAP PHASE ESTIMATION CAN PARTIALLY COMPENSATE FOR TIME VARYING CHANNEL PERTURBATIONS AND NONSTATIONARY INTERFERENCE EFFECTS SO AS TO REDUCE DECODING ERRORS FOR SPREAD SPECTRUM COMMUNICATIONS. FOR FM RECEPTION, REPLACEMENT OF A PHASE LOCKED LOOP DEMODULATOR BY A HOPFIELD MAP DEMODULATOR SHOULD REDUCE MEAN-SQUARED ERROR BETWEEN DEMODULATED AND TRANSMITTED SIGNALS, AND SHOULD LEAD TO MORE GRACEFUL DEGRADATION OF PERFORMANCE THAN THE SUDDEN SIGNAL DROP-OUT PRESENTLY EXPERIENCED IN MOBILE FM RADIO RECEIVERS. THE PROPOSED PHASE I EFFORT INVOLVES COMPUTER SIMULATIONS AND ANALYSIS TO DEMONSTRATE THE EXPECTED IMPROVEMENTS. ANTICIPATED BENEFITS/POTENTIAL APPLICATIONS - UTILIZATION OF SPREAD SPECTRUM TECHNIQUES BY DOD AND OTHERS IS INCREASING BECAUSE OF ROBUSTNESS TO INTERFERENCE AND FADING. IMPROVEMENT OF SUCH TECHNIQUES HAS HIGH MARKET POTENTIAL FOR SATELLITE AND MULTIPLE ACCESS COMMUNICATIONS, E.G., CELLULAR TELEPHONES. OTHER APPLICATIONS OF VLSI NEURAL NETWORK MAP ANGLE DEMODULATION INCLUDE FM RADIO RECEIVERS FOR HOME AND CAR.